This invention relates to an RJ-45 style modular connector. These it, connectors have a female portion known as a jack or socket and a male portion called a plug. The present invention concerns an improved plug for an RJ-45 connector. The jack typically has a housing containing a planar array of parallel contacts which make sliding, electrically-conducting contact with the plug. The jack contacts often are metal blades having a cantilevered portion that is biased into engagement with the plug in the nature of a leaf spring. For this reason the jack contacts are referred to herein as spring contacts.
RJ-45 connectors were originally developed to terminate flat telephone cable and are very well suited to that application. In recent years these connectors have also been used for data communications purposes including terminations of unshielded twisted pair (UTP) cable for high speed data transmission. The latter application has been divided into data transmission speeds called categories with category 5 being data transmission up to 150 megabits per second. At this data rate, the connector becomes an integral part of data transmission wiring and has a large effect on the maximum rate of data transmission. This invention relates to a connector plug that is capable of terminating UTP cable in a category 5 data transmission network.
A UTP cable comprises at least two individual, insulated wires. A wire, as used herein, will refer to the combination of a conductor and a surrounding insulation layer. Two such wires, known as a pair, are twisted together. For most data communications applications the UTP cable will have four pairs. The plurality of twisted pairs are gathered together within an outer insulation jacket. This imparts a configuration that is relatively round compared to flat cables. In other words, the gathered pairs of the UTP cable define a two-dimensional cross-section that will be referred to herein as a bundled cross-section. The bundled cross-section may include one or more inner wires in the interior of the bundle and a plurality of surrounding outer wires. The bundled cross-section contrasts with a linear configuration which, as used herein, is a group of wires, conductors or contacts laid side-by-side next to one another in a flat, planar array which defines essentially a one-dimensional cross-section (ignoring for this definitional purpose the thickness of each wire). That is, a linear configuration or array is one in which the centers of the individual wires, when viewed in cross-section, define a straight line.
Using a standard RJ-45 connector with UTP cable is difficult because the cable is bundled but the RJ-45 connector's contacts must terminate in a linear fashion. That is, when using an RJ-45 connector on UTP cable the two-dimensional, bundled cross-section of the UTP cable must be transposed to a one-dimensional configuration. In a sense the problem is one of fitting a round peg into a flat hole. The prior art solution to this problem is to untwist the wires, arrange them linearly in the correct order and insert the wires into the connector and crimp the connector onto the wires. But untwisting of the individual wires of the cable causes degradation of the data transmission capability. One reason for this is the linear array is subject to cross talk on the nested pairs at the center of the array. Further, the strain relief action of existing connectors tends to smash the individual conductors into an oval shape which further degrades their transmission capability.